1. Field of the Invention
The present invention relates to an image recording medium feeding device for feeding an image recording medium such as a stimulable phosphor sheet or the like.
2. Description of the Related Art
There is known a system for recording radiation image information of a subject such as a human body with a stimulable phosphor, and reproducing the recorded radiation image information on a photosensitive medium such as a photographic film, or displaying the recorded radiation image information on a display device such as a CRT or the like.
The stimulable phosphor is a phosphor which, when ex-posed to an applied radiation such as X-rays, xcex1-rays, xcex3-rays, electron beams, ultraviolet radiation, or the like stores a part of the energy of the radiation, and, when subsequently exposed to applied stimulating rays such as visible light, emits light in proportion to the stored energy of the radiation. Usually, a sheet provided with a layer of the stimulable phosphor, or a stimulable phosphor sheet, is used in the art for ease of handling.
The above known system includes a recording section for recording radiation image information of a subject on a stimulable phosphor sheet, a reading section for photoelectrically reading the radiation image information recorded on the stimulable phosphor sheet by applying stimulating rays to the stimulable phosphor sheet, and an erasing section for erasing remaining radiation image information from the stimulable phosphor sheet after the recorded radiation image information has been read. The recording section, the reading section, and the erasing section are incorporated together in a radiation image information reading apparatus in which the stimulable phosphor sheet is circulated or reciprocated.
The stimulable phosphor sheet is coated on its surface with a protective material such as silicone for protection against damage. When the stimulable phosphor sheet is cyclically used in the radiation image information reading apparatus, the surface of the stimulable phosphor sheet is frequently brought into contact with a feeding system in the apparatus, causing the coated protective material to be scraped off due to wear. Therefore, the surface of the stimulable phosphor sheet tends to be smeared or damaged, with the result that the stimulable phosphor sheet may be unable to produce high-quality radiation image information.
One solution is to employ a feeding system for gripping opposite longitudinal marginal edges, which are an image-free area, of a stimulable phosphor sheet to feed the stimulable phosphor sheet. Specifically, the opposite longitudinal marginal edges of the stimulable phosphor sheet are gripped by paired rollers, which are rotated to deliver the stimulable phosphor sheet, while the opposite longitudinal marginal edges are being guided by guide members.
The radiation image information reading apparatus has a plurality of curved feed paths along which the stimulable phosphor sheet is curved when it is fed. When the stimulable phosphor sheet is fed along a curved feed path by a pair of rollers gripping the opposite longitudinal marginal edges of the stimulable phosphor sheet, the stimulable phosphor sheet is liable to bulge in its central region. Accordingly, it is difficult to feed the stimulable phosphor sheet smoothly along a desired curved feed path.
In particular, the stimulable phosphor sheet cannot smoothly be fed by pairs of rollers gripping its opposite longitudinal marginal edges along a sharply curved feed path through 90xc2x0 or more, for example, 180xc2x0, which is often employed in efforts to reduce the size of the radiation image information reading apparatus.
The above problem also occurs with a radiation image information reading apparatus which comprises a loading section for loading a cassette housing a stimulable phosphor sheet with radiation image information recorded thereon, a reading section for photoelectrically reading the radiation image information recorded on the stimulable phosphor sheet by applying stimulating rays to the stimulable phosphor sheet, and an erasing section for erasing remaining radiation image information from the stimulable phosphor sheet after the recorded radiation image information has been read.
Furthermore, various other image recording mediums such as a photographic film or the like in general use cannot smoothly be fed along sharply curved feed paths by pairs of rollers that grip their opposite longitudinal marginal edges only in order to protect recorded areas.
It is a major object of the present invention to provide an image recording medium feeding device which is of a relatively simple structure for smoothly and reliably feeding an image recording medium along a curved feed path using opposite longitudinal edges of the image recording medium.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.